I understand your point, but much of what you mention - alcoholism, obesity, substance abuse etc - is an illness in itself that exacerbates other medical problems. Deciding not to have a vaccination isn't an illness.
I think it's naive to say that one's free will plays no role in any of those things. For obesity in particular, I don't think it's reasonable to believe that every obese or overweight person has some sort of illness that causes it, because that's half the population. Moreover, I suspect there are mental illnesses or at least mental health issues in play for many of the more conspiracy-minded anti-vaxers.
Pregnancy is a necessary part of life for society to exist at all. Anti vaxxing is not.
It's not as if the world's going to run out of people. If someone knows that their pregnancy is going to be high-risk or complicated, they're choosing to assume that risk, just as someone who doesn't get vaccinated is choosing to assume the risk of getting seriously ill from covid.
Car accidents are by definition accidental and unpredictable so not an issue of negligence.
Many, perhaps most, car accidents are caused by negligence. That's certainly true of drunk driving accidents.
I just don't see why an unvaccinated person with severe covid should go to the back of the line while a drunk or reckless driver who almost killed himself in the process of killing a family of four, or a lifelong smoker with lung cancer, is considered a higher priority.